Gas lift valve



Dec. 14, 1965 cu 3,223,109

GAS LIFT VALVE Filed May 16, 1962 5 Sheets-Sheet l V E TV I Fig.5

- INVENTOR 1% Leslie L. Cummings ATTORNEYS Dec. 14, 1965 CUMMINGS 3,

GAS LIFT VALVE Filed May 16, 1962 5 Sheets-Sheet 2 INVENTOR' Leslie L. Cummings BY ATTORNEYS Fig.7

Dec. 14, 1965 1.. CUMMINGS GAS LIFT VALVE 5 Sheets-Sheet 3 Filed May 16, 1962 Fig.8

- INVENTOR Leslie L. Cummings WW Fig.9

Fig.|l

United States Patent 3,223,109 GAS LIFT VALVE Leslie L. Cummings, 44318 W. Alabama, Houston, Tex. Filed May 16, 1962, Ser. No. 195,099 22 Claims. (Cl. 137155) This invention relates to well tools and more particularly to air or gas lift valves for use in producing oil wells or the like by controlling the admission of gas or air into a column of liquid in the well to lift the column and aid in flowing the liquid from the well.

In conventional gas lift systems, the well equipment includes one or more strings of relatively small pipe called the tubing which is inserted inside a large diameter pipe called the casing. Gas or air under pressure is introduced into the annular space or annulus between the tubing and the casing and is injected through suitable gas lift valves located at longitudinally spaced points along the tubing into the column of liquid inside the tubing in order to lift the liquid in the tubing to the surface.

The gas lift valves may be mounted exteriorly of the tubing string and communicate with the interior of the tubing through suitable ports in the wall of said tubing, or may be removably mounted in specially prepared landing nipples constituting sections of the tubing wherein each valve is positioned laterally of the principal tubing bore, the nipples having suitable gas inlet ports, so that the tubing bore remains open for the passage of other tools therethrough as is fully shown and described in the patent to Canalizo, 2,954,043. The valves may also be removably positioned in the tubing bore or be fixed in position in the tubing bore. Alternatively, the gas lift valves may be mounted on the tubing string itself and be disposed thereabout as is fully explained and disclosed in the patent to Cummings, 2,642,889.

The gas lift valves may be of three general types, the pressure operated type which are generally biased toward a closed position by any suitable means, as by a charge of compressible gas, and which open when the pressure of the air or gas in the annulus exceeds a predetermined value; tubing pressure responsive valves which open when the pressure within the tubing exceeds a predetermined value; and differential pressure valves which are responsive to the pressure differential between the tubing and the annulus.

The tubing pressure responsive valves and the pressure differential responsive valves open when the height of the column of liquid in the tubing to be lifted attains a predetermined value, but they tend to remain open for a period of time so long that more than enough gas to lift the column of liquid is likely to be admitted into the tubing, thus causing waste of gas. The annulus pressure responsive valves open regardless of the height of the column of the liquid in the tubing and therefore may also cause loss of gas since the column of liquid may not at the time of opening have attained the desired height. Since, for maximum efficiency of operation, it is desirable that each valve open only when the annulus pressure reaches a predetermined value and the height of the column of the liquid or oil in the tubing has also attained a predetermined height, so that the valve will not open if the column of liquid has not attained the predetermined height even if the annulus pressure has at tained its predetermined value, and, conversely, the valve also will not open if the column of liquid has attained the predetermined height, but the annulus pressure has not attained its predetermined value. Moreover, if two or more strings of tubing are inserted in the casing and each must be provided with gas lift valves, gas lift valves which are responsive only to the annulus pressure may be mounted on only one of the strings of tubing since if two or more strings of tubing were provided with the annulus pressure responsive gas lift valves, whenever one or more of the valves of one of the strings opens, the valves of the other strings would thereafter not open since the flow of the gas into such tubing string whose valve opened first would immediately decrease the pressure in the annulus and the valves of the other strings would never open.

Accordingly, an object of this invention is to provide a new and improved gas lift valve which will open only when the annulus pressure attains a predetermined value and the pressure differential between the tubing and the annulus exceeds a predetermined value.

Another object is to provide a gas lift valve which will close whenever the pressure in the annulus of the well drops below the predetermined value.

Still another object is to provide a gas lift valve which will open only when a column of liquid of predetermined height is present within the tubing above the valve and the pressure within the annulus of the well exceeds a predetermined value.

A further object is to provide a gas lift valve which automatically opens and closes when predetermined pressure conditions exist within the tubing and the annulus to prevent waste of the lifting gas by causing opening of the valve to permit flow of lifting gas into the tubing only when the proper conditions obtain within the tubing and the annulus and which closes whenever the pressure conditions within the annulus require closing thereof to prevent wastage of gas.

A still further object is to provide a new and improved gas lift valve, a plurality of which may be used on the same string or on a plurality of strings within a well and which may be set to open at the same or different annulus pressures provided that the heights of the columns of liquid in the tubings above the valves attain predetermined heights.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a view, partly in section and partly in elevation, of a gas lift valve embodying the invention installed in a side pocket of a mandrel connected in a string of tubing disposedin a well casing;

FIGURE 2 is an enlarged view, partly in section and partly in elevation, with some parts broken away, of the gas lift valve of FIGURE 2, showing the valve in closed position;

FIGURE 3 is a View similar to FIGURE 2 showing the valve in open position;

FIGURE 4 is a sectional view taken on line 44 of FIGURE 3;

FIGURE 5 is a view, partly in section and partly in elevation, with some parts broken away, showing a tubing string provided with a modified form of the valve illustrated in FIGURES 1 through 4;

FIGURE 6 is a view, partly in section and partly in elevation, of another form of the gas lift valve embodying the invention;

FIGURE 7 is a fragmentary sectional view of a portion of the gas lift valve illustrated in FIGURE 6;

FIGURE 8 is a fragmentary sectional view of another modified form of the gas lift valve illustrated in FIG- URE 6;

FIGURE 9 is a sectional view taken on line 9-9 of FIGURE 8;

FIGURE 10 is a schematic sectional view showing a tubing string provided with the gas lift valves embodying the invention; and,

FIGURE 11 is a vertical, sectional schematic view of a well having two strings of tubing each provided with gas lift valves embodying the invention.

Referring now more particularly to FIGURES 1 through 4 of the drawing, a gas lift valve 20 embodying the invention is receivable in the offset pocket 22 of a landing nipple or mandrel 23, the pocket being laterally offset from the longitudinal bore 24 of the mandrel. The mandrel 23 is connectable in a tubing string T to form a section thereof and is connected at its upper and lower ends to the usual tubing sections 25. The tubing of course extends through the usual well casing 27 of the well. The tubing and the casing may extend from a producing formation to the surface of the ground and may be provided with a packer, not shown in FIGURE 1, below the mandrel in a manner well known to the art.

The pocket may be formed of an upper section 28 and a lower section 2 welded together and having a common longitudinal bore 30 opening upwardly. The pocket may be eccentrically affixed in the wall of the mandrel, as by the Welds 31. An internal annular locking recess 32 near the upper end of the upper pocket section is engageable by a lock dog 34 of the removable gas lift valve 20, as will be more fully explained below.

A plurality of ports 36 through the wall of the lower pocket section provide fluid communication between the exterior of the nipple and the interior of the pocket and a discharge port 37 at the lower end of the pocket provides fluid communication therethrough between the bore 30 of the pocket and the bore of the tubing string.

The valve 20 includes a tubular chamber body 40 whose upper end is closed by a charging sub 41 having a charging valve 42 threaded in an opening in the upper end thereof and a plug 43 threaded into the sub above the charging valve. The charging valve permits flow therethrough into the chamber 44 of the chamber body but prevents reverse flow from the chamber. The charging valve may be similar to the well known pneumatic valve used for the introduction of air into pneumatic tires. The locking mandrel 45 which carries the expansible and retractible lock dog or latch means 34 is threaded onto the upper reduced end 46 of the charging sub to protect the plug from damage. An O-ring or other suitable sealing means 47 is disposed in an external annular groove of the charging sub 41 and seals between the tubular chamber body 40 and the charging sub.

An intermediate tubular body 48 is threaded into the lower end of the chamber body 40 and is provided with a plurality of lateral gas entry ports 49 through its wall for a purpose to be more fully hereinafter described. A tubular lower sub 50 is threaded into the lower end of the intermediate tubular body and is provided with threads 51 at its lower end whereby the guide and flow cap 53 may be threaded thereon. The guide and flow cap is provided with downwardly opening ports 54.

A valve mandrel 55 having a bore 56 open at its upper end has mounted on its lower end a tubular control sleeve or closure member 58 closed at its lower end and constructed of a resilient material such as rubber, neoprene, and the like. The outer surface of the closed lower end of the closure sleeve approximates a hemisphere. The closure sleeve is held in position on the lower end of the valve mandrel by an inwardly extending annular flange 60 at the upper end of the closure sleeve which resiliently engages an upwardly facing annular shoulder 61 on the outersurface of the lower portion of the valve mandrel and by the downwardly facing internal annular shoulder 63 of the intermediate tubular body which engages the upper annular end surface of the closure member The valve mandrel is inserted through the lower end of the intermediate tubular body to protrude upwardly therethrough and is held in place in the intermediate tubular body by the engagement of the external annular shoulder 65 thereof with an internal annular shoulder 66 formed by a counterbore of the intermediate tubular 4 body and by a nut 68 and a lock nut 69 threaded on the upper end of the valve mandrel, the nut 68 engaging the upper end of the intermediate tubular body 48.

An O-ring or other suitable seal means 71 disposed in an annular groove in the external surface of the valve mandrel seals between the mandrel and the intermediate tubular body above the downwardly facing shoulder 66 thereof while a similar seal means 71a disposed in an annular groove in the intermediate body 48 seal between the intermediate body and the chamber body 40.

An O-ring or other suitable sealing means 72 is disposed in an annular external groove of the lower sub which seals between the lower sub 50 and the intermediate tubular body below the ports 49. The outer surface of the valve mandrel is relieved at its lower end 73 to provide an annular space 74 between the lower outer surface of the valve mandrel and the inner surface of the closure member. Lateral ports 75 of the valve mandrel provide communication between the bore 56 of the valve mandrel and the space 74 between the closure member and the mandrel.

The cylindrical inner seal surface 77 of the body 48 below the shoulder 63 includes the area in which the ports 49 are located. The closure sleeve is of such free diameter as to normally engage the cylindrical seal surface 77 to close the ports 49 and to function in a manner to be hereinafter more fully described.

A retainer or support member 86 having a concave upper surface 81 conforming to the convex lower outer surface of the closure member supports the lower end of the closure member and is in turn supported by means of its downwardly facing annular shoulder 83 on the upper end of the lower sub 50. A plurality of circumferentially spaced longitudinal slots 85 in the outer surface of the retainer provide passages for the flow of fluids therepast.

A check valve 86 is secured to the lower end of the retainer by a cap screw 87 which extends into a suitable threaded downwardly opening bore of the retainer. The check valve is of a resilient substance or material, such as rubber, neoprene, or the like, and has a lower lip 89 which provides a cylindrical outer surface which is sealingly engagea-ble with the internal cylindrical seal surface 99 of the lower sub 50 located below the lower end of the retainer. The cup shaped check valve is disposed in the substantially concave downwardly facing recess 92 in the lower end of the retainer 80.

The construction of the check valve permits flow of fluid or lifting gas downwardly through the slots of the retainer and thence past the lower lip of the check valve, the lip of the check valve flexing inwardly to permit such flow. Flow of fluid or gas in an upward direction is prevented by the sealing engagement of the lower lip with the cylindrical seal surface of the lower sub. The lip of the seal element is normally in closed position in contact with the bore Wall of the lower sub but readily flexes inwardly to permit downward flow therepast.

An upper sealing means or assembly 1% shown to be of the V-type is disposed on the outer surface of the intermediate tubular body 48 and is retained thereon between an upwardly facing external annular shoulder 1&2 of the intermediate body above the ports 49 and the lower end of the chamber body 48. A similar lower sealing means 104 disposed on the outer surface of the lower sub 50 between a downwardly facing external annular shoulder 105 of the lower sub and the upwardly facing annular shoulder 107 of the guide and flow cap 53. The upper and lower sealing means Tilt) and 1&4, respectively, are adapted to sealingly engage the bore Wall 109 of the pocket 22 above and below the ports 36.

The lower sub 50 has an internal annular flange which provides an internal annular shoulder 110 on which rests the annular valve seat 111 which is secured to the lower sub by any suitable means as by silver soldering. A tubular valve cage 113 is disposed in the lower sub above the,

valve seat with its lower end abutting the upwardly facing annular shoulder 114 of the lower sub. The valve cage is provided at its upper end with an internal annular flange 115 through which slidably extends the pressure differential responsive valve 116. The valve cage has lateral apertures 117 above the annular shoulder 118 of the lower sub formed by the enlargement of the bore 11? of the lower sub. The pressure differential responsive valve is biased toward its upper open position, illustrated in FIGURE 3, by a spring 125 disposed about the valve whose lower end bears against the annular flange 115 of the valve cage and whose other end bears against the lower surface of the external annular flange 121 of the valve 116.

The upper reduced end portion 123 of the valve extends into the downwardly opening blind bore 125 of a spider 126 disposed in the upper enlarged portion 127 of the bore 119 of the lower sub. The upper reduced portion 123 of the pressure differential responsive valve has a close fit with the cylindrical surface defining the blind bore 125 of the spider which is close enough to prevent any appreciable flow of fluids therepast so that the pressure within the bore above the pressure differential valve will not tend to escape therebetween. A seal such as an O-ring could be provided in an external annular groove of the reduced portion of the pressure differential valve to seal between the spider and the valve but such seal would increase the frictional forces between the spider and the pressure differential responsive valve and would thus decrease the sensitivity of the pressure differential responsive valve.

Downward movement of the spider is limited by the engagement of its lower end with the internal annular shoulder 12% of the lower sub and upward movement of the spider is limited by its engagement with the snap ring 1319 which is received in a suitable internal annular groove of the lower sub. The spider has a lateral port 132 whose inner end opens into the upper end of its blind bore 125 and whose outer end opens into the external annular flow recess 133 of the spider. The spider is provided with a pair of external upper and lower seal means, such as O-rings 135 and 136, respectively, which are disposed in suitable external annular recesses of the spider. The O-rings seal above and below the flow recess with the internal surface of the lower sub defining the upper enlarged portion 127 of the bore 119 of the lower sub above and below the lateral port 137 of the lower sub which communicates with the enlarged portion of the bore of the lower sub and with the flow recess 133 of the spider. The port 137 opens to the exterior of the lower sub above the lower sealing means 1114.

The spider has a plurality of longitudinally extending flow passages 14%) which open downwardly into the bore 11? of the lower sub and upwardly into the region of the lower sub below the check valve 86.

The pressure differential responsive valve 116, when the gas lift valve is disposed in the oflset pocket 22 or" the mandrel, is exposed to the pressure within the bore of the tubing through the port 37 of the pocket and the downwardly opening ports 54 of the flow and guide cap 53. The tubing pressure acts upwardly on the area of the pressure differential responsive valve 116 which lies within the circle of contact between the valve seat 111 and the lower arcuate end of the pressure differential responsive valve. The pressure within the annulus between the tubing and the well casing 27 acts on the upper surface of the upper reduced portion 123 of the pressure differential responsive valve since fluid pressure from the annulus may now enter into the upper portion of the blind bore 125 of the spider through the port 132 and the annular flow recess 133 of the spider, the lateral port 137 of the lower sub, the bore of the pocket 22 and the lateral port 36 of the pocket. It will be apparent therefore that the annulus pressure tends to move the pressure differential responsive valve 116 downwardly to its closed 6 position while the tubing pressure and the force of the spring tend to move the valve to its upper open position.

It will now be seen that, since the areas of the pres sure differential valve exposed to the annulus and tubing pressures are equal, the force of the spring 120 will be effective to move the Valve to its upper open position whenever the tubing pressure increases above a predetermined value which is, however, lower than the value of the annulus pressure, it being apparent that the annulus pressure is maintained at a higher value than the tubing pressure during gas lift operations. Thus, it is the load of spring 120 that determines the differential pressure at which the valve operates. This is independent of the pressure responsive portion of the gas lift valve. For instance, chamber 44 might be charged to 500 psi. so that intake ports 49 will open when the annulus pressure rises above 500 p.s.i. and will close when it falls below 500 p.s.i. If spring 120 is loaded to equal 200 p.s.i. then, whenever the difference between the annulus and tubing pressures decreases to 200 p.s.i., the spring 120 will lift valve 116 to its open position. Thus, the valve 116 would open when the annulus and tubing pressures were 400 and 200 p.s.i., respectively, 500 and 300 p.s.i., respectively, or 600 and 400 p.s.i., respectively. By varying the loading of spring 120, the differential pressure can be varied as desired Chamber 44 is charged beforehand to the desired pressure. The annulus is generally charged to a slightly higher pressure. By increasing the annulus pressure, a higher column of liquid will be needed in the tubing to open valve 116, but more cubic feet of gas will be stored in the annulus. The valve will still operate at the same differential because the load of spring 120 is not changed.

In use, before the gas lift valve is installed in position in a landing nipple 23 of a tubing string whose lower end is open to permit well fluids from a producing formation to flow into the tubing, the annulus below the landing nipple being closed by a packer in the usual manner, the chamber 44 is charged with a compressible fluid, such as air or gas, to a predetermined operating pressure through the charging valve 42 after which the plug 43 and the locking mandrel 45 are connected to the charging sub. The pressure of the charge in the chamber 44 is then communicated through the port 75 of the valve mandrel to the space 74 between the mandrel and the closure member or control sleeve 58 thereby holding the closure member in closing or sealing contact with the cylindrical inner seal surface 77 of the intermediate body across the lifting gas intake ports or slots 49 of the intermediate body. It will be evident that as long as the pressure exteriorly of the ports 41 is less than that in the interior of the chamber 44 and the space 74 between the valve mandrel and the closure member, the closure member will be maintained in closed position and in sealing contact across the gas intake ports 49 forming a tight closure therefor. The slots are sufficiently narrow that the material of the valve member does not extrude therethrough to any material degree. The closure member is retained in position on the lower end of the valve mandrel by the concave upper surface 81 of the retainer 80 and by the confinement of the flange 60 of the closure member between the upwardly facing shoulder 61 of the valve mandrel and the downwardly facing shoulder 63 of the intermediate body.

The gas lift valve 21 is then lowered into the tubing string in the well known manner by means of a flexible line lowering mechanism (not shown) and is moved laterally in the landing nipple 23 in a manner well known in the art to position the valve in the pocket. The valve is lowered in the pocket until its downward movement is stopped by the engagement of the external flange of the locking mandrel with the upper end of the pocket 22, the locking dog or latch means 34 being cammed resiliently inwardly against the biasing means (not shown) in the locking mandrel as the valve is lowered into the pocket. The locking dog or latch means is moved outwardly into the locking recess 32 by the biasing means to releasably hold the valve in position in the pocket. The upper and lower sealing means 160 and 104 sealingly engage the bore wall 1619 of the lower pocket section above and below, respectively, the ports 36 of the landing nipple above and below the intake ports 49 and 137 of the valve. The pressure in the annulus between the tubing string and the casing is increased or brought to its operating level by the injecting of gas or air thereinto at the surface of the well. If the lifting gas pressure in the annulus exceeds the present or preloaded pressure in the chamber of the valve, the closure member moves inwardly to open the intake ports 49 whereupon the lifting gas will tend to flow therethrough into the intermediate body, through the slots 85 of the retainer and past the check valve 86 to the longitudinal passages 140 of the spider and thence through the bore 119 of the lower sub. However, such fiow of the lifting gas cannot take place since the pressure differential valve is still in its lower closed position in engagement with the valve seat 111 closing the discharge port 112 thereof. The pressure differential valve is in its closed position since the lifting gas pressure is communicated to the blind bore 125 of the spider and tends to hold the pressure differential valve in its lower closed position.

When the well liquid, which enters into the bore of the tubing string through its open lower end, rises to a predetermined height above the gas lift valve, the hydrostatic pressure exerted by the column of liquid acting against the lower end of the pressure differential valve 116 rises above a predetermined value, which however is below the pressure of the lifting gas in the annulus, and the pressure differential valve 116 moves upwardly to its open position to open the gas discharge passage or port 112 since the spring 120 also tends to move the pressure differential valve to its open position. Since the pressure of the lifting gas is now greater than the pressure within the tubing string, the lifting gas flows inwardly through the intake ports 49, since the closure member is now in its open position; through the longitudinal slots 85 of the retainer 86 past the check valve whose lip now moves out of sealing engagement with the cylindrical sealing surface 99 of the lower sub; through the longitudinal flow passages 140 of the spider into the bore 119 of the lower sub below the spider; through the lateral ports 117 of the valve cage 113; thence through the discharge passage 112 of the annular valve set and the flow passages 54 of the flow and guide cap 53 into the lower portion of the pocket below the sealing means 104 of the gas lift valve; and thence through the port 37 of the pocket into the bore of the mandrel 23. The gas entering the column of liquid raises the pressure in the tubing and lifts the liquid to the surface in the usual manner.

It will be noted that the pressure differential responsive valve 116 will prevent any flow of lifting gas into the tubing, even if the annulus pressure exceeds the pressure necessary to move the closure member 58 to its open position, until the proper conditions obtain within the well, i.e., the pressure differential between the annulus and bore of the tubing string drops to a predetermined value which is caused by the column of liquid in the tubing string above the gas lift valve attaining a predetermined height.

Since the rate of flow of the lifting gas through the gas lift valve now exceeds the rate of injection of the lifting gas into the annulus at the surface, the pressure in the annulus decreases. When the pressure in the annulus falls below that in the chamber 44 of the gas lift valve, the pressure of the charge of air or gas in the chamber 44 is effective to move the closure member 58 into engagement with the cylindrical sealing surface 77 to again, close the intake ports 49 and all flow of the lifting gas through the gas lift valve will now cease even though the pressure differential responsive valve 116 may still be in its open position. The closure member may not close the intake ports 49 to stop all flow through the valve at this time but may throttle or regulate the fiow of lifting gas so that the rate of flow therethrough equals the injection rate. As the column or slug of liquid is expelled from the tubing at the surface, the pressure in the tubing decreases. When the tubing pressure falls below a predetermined value, the differential in the pressure acting on the upper and lower ends of the pressure differential responsive valve 116 causes the pressure differential responsive valve 116 to be moved back to its closed position, since the force of pressure of the lifting gas in the annulus acting on the upper end of the pressure differential responsive valve 116 becomes great enough to overcome the forces exerted on the'valve by the spring and the fluid pressure within the tubing acting on the lower end of the pressure differential valve. The valve is now again in its initial position and as the injection of the lifting gas into the annulus at the surface continues, the pressure in the annulus again rises above the predetermined value necessary to cause the closure member 58 to be moved to its open position and the pressure differential valve 116 will again open when the liquid in the tubing again rises to the predetermined height at which time the valve 116 will again open to permit gas to be injected from the annulus into the tubing to lift another column or slug of liquid to the surface.

It will be noted that at no time during the operation of the gas lift valve can the liquid from the formation in the tubing string flow into the annulus through the gas lift valve since the check valve 86 closes off upward flow through the valve by the sealing engagement of its lip with the sealing surface 99 of the lower sub 50.

It will thus be seen that for any predetermined pressure condition of the lifting gas within the annulus, the gas lift valve illustrated and described in FIGURES 1 through 4 will open only when the desired predetermined conditions obtain in the tubing string, i.e. when a column of liquid of predetermined height is in the tubing string above the gas lift valve, and that the valve will close whenever the pressure within the annulus decreases below a predetermined value.

It will further be seen that the gas lift valve has means providing lifting gas intake port means, such as the ports 49 through which lifting gas from the annulus is permitted to flow into a passage of the valve, i.e., the bore of the intermediate body below the intake ports and the bore of the lower sub, and has discharged port means, such as the passage 112 of the valve seat and the ports 54 of the flow and guide cap 53, which communicate with such passage of the valve and with the interior of the tubing. It will further be seen that valve means responsive only to the pressure of the annulus are provided for closing the intake port means whenever the pressure within the annulus drops below a predetermined value and that valve means responsive to the pressure differential between the tubing and the annulus are provided for opening the discharge port means whenever such pressure differential drops below a predetermined value, which occurs when a column of liquid of predetermined height is present in the tubing above the discharge port means.

A number of the landing nipples or mandrels 23 may be included at spaced intervals in the tubing string whereby a plurality of gas lift valves may be mounted therein. The gas lift valves at different levels in the tubing may be set to operate at the same or different pressures, and any of the valves may be installed or removed from any landing nipples by means of flexible line operating mechanisms without disturbing any of the valves or landing nipples in a manner already known in the art.

The gas lift valve 20 may be mounted on the exterior of a landing nipple 150, which is connectable by the usual couplings (not shown) in a string of well pipe or tubing and which may also be disposed in the well casing 27 of a well. The landing nipple 150 is provided with an external injection lug 151 having an injection passage 152 which opens into the bore of the landing nipple through the lateral port 153 thereof. The upper portion of the injection passageway is enlarged and threaded as at 154 to receive the lower reduced threaded portion 51 of the lower sub of the gas lift valve 20, the locking mandrel 45 is then replaced by a protective cap 45a to protect the plug 53 and the charging sub 41. Since the valve is now on the exterior of the nipple, the upper and lower sealing means 100 and 104 are unnecessary and are removed.

It will be apparent that the gas lift valve 20 functions in exactly the same manner when mounted on the exterior of the landing nipple 150 as when disposed within the pocket 22 of the landing nipple 23. The landing nipple 150 may also be provided with a protective guide lug 157 disposed above the upper end of the valve 20 to prevent damage to the valve as the tubing is lowered into or pulled from the well.

Referring now particularly to FIGURES 6 and 7 of the drawing, the modified gas lift valve 200 embodying the invention includes a tubular body or mandrel 201 normally having the same dimensions as the tubing string in which it is to be connected to form a section thereof. The upper and lower ends of the mandrel are externally threaded whereby they may be connected to adjacent sections of a string of Well tubing by the usual coupling collars (not shown). The mandrel 201 is provided with a plurality of circumferentially spaced discharge ports 202 through which lifting gas may be introduced into the tubing string from an annular passage 203 formed about the mandrel by the mandrel and a sleeve 205 mounted on the mandrel. The sleeve 205 is mounted on the exterior of the mandrel and includes a lower closure section or ring 206, a port section 207, and a top closure section 208. The lower closure section 206 of the sleeve is provided with an internal annular flange 209 having a filler port 210 which has an enlarged bore portion 211 in which is disposed the spring 212 which biases the ball check valve 213 toward the valve seat 214 threaded in the outer enlarged portion of the filler port 210. The orifice 215 of the valve seat may be closed at its outer end by a plug 217. It will be apparent that when the plug 217 is removed, gas or air under pressure may be caused to flow upwardly through the filler port 210, reverse flow being stopped by the engagement of the check valve 213 with the valve seat 214.

The lower closure section of the sleeve is held against downward movement on the mandrel 201 by the nut 220 and the lock nut 221 threaded on the mandrel. An ring 223 or other suitable sealing means is disposed in a suitable annular recess of the mandrel to seal between the mandrel and the internal flange 209 at the lower end of the lower section of the sleeve.

The port section of the sleeve is provided with a plurality of intake slots or ports 225 which open into the lower end of the passage 203 and which may be closed by a tubular closure member 226, formed of a resilient substance, such as rubber, neoprene, or the like. The lower end of the closure member is held in position in the sleeve by means of a closure ring 228 whose external annular flange 225 is disposed between the lower and upper ends of the port section 207 and the lower closure section 206 of the sleeve, respectively, and which may be secured to the lower closure section in any suitable manner, as by the weld 230. The lower end of the closure member is provided with an external annular flange 232 which is engaged between the beveled downwardly and outwardly extending annular shoulder 233 of the port section and the upwardly facting annular shoulder 235 of the closure ring 228. An O-ring or other suitable sealing means 237 may be disposed in an external annular recess of the closure ring above the external flange 229 thereof to seal between the port section of the sleeve and the closure ring.

A tubular support and guide member 240 has a lower end portion 241 which telescopes into the upper end of the closure ring 228 and an external downwardly and outwardly extending flange 242 which engages the upper end of the closure ring, which is of similar configuration, to support the guide and support member on the closure ring. The guide and support member has an internal diameter greater than the external diameter of the mandrel so that fluid may flow upwardly and downwardly therebetween.

The upper end of the closure member is provided with an internal annular flange 244 which is received in an external annular recess 245 of the mandrel. The upper end portion of the flange is held in the recess by the tubular retainer 248 whose downwardly and outwardly extending annular shoulder 249 engages the upper end of the closure member and whose internal cylindrical lower surface 250 engages the exterior of the upper portion of the closure member to hold it against outward displacement from the recess 245. The retainer 248 is held against movement on the mandrel 201 by an suitable means, such as the tangential locking pins 252 which extend through suitable aligned recesses of the mandrel and of the retainer, as is well known in the art. A suitable O-ring or other sealing means 253 is disposed in an external annular recess of the mandrel to seal between the retainer and the mandrel below the tangential locking pins 252.

The closure ring, the lower closure section and the closure member form a chamber 255 about the mandrel which may be filled with air or gas under pressure through the filler port 210. The force of the gas under pressure will cause the closure member to engage the internal cylindrical sealing surface 257 of the port sleeve to close the ports 225 thereof until the pressure exteriorly of the port sleeve exceeds the pressure of the gas in the chamber 255 and moves the closure member to the open position illustrated in FIGURE 6.

The lower end of the retainer provides a downwardly and outwardly extending support surface 260 for the closure member when the closure member is in its closed position. The retainer has a plurality of external longitudinal slots 262 which permit flow of fluids upwardly through the passage 203 from the slots 225 to the gas discharge ports 202 of the mandrel when the closure member is in its open position. A tubular check valve 265 is disposed in the passage 203 between the intake and discharge ports. The check valve has a lower end portion received in the enlarged portion 266 of the bore of the retainer 248 and has an internal annular flange 267 received in the external annular recess 268 of the mandrel. The internal flange is held against upward displacement in the recess 268 by means of the retainer rings 269 and 270 disposed on opposite sides of the O-ring or sealing means 272 which seals between the mandrel and the lower portion of the check valve above its flange. The upper free end or lip 275 of the tubular check valve is adapted to engage the internal annular seal surface 276 of the port section 207 of the sleeve above the upper end of the retainer to prevent flow of fluids from the discharge ports 202 downwardly through the slots 262 and to the intake ports 225 of the port section of the sleeve. The upper internal surface of the retainer may be beveled upwardly and outwardly, as at 277, to provide a support for the check valve.

The top closure section 208 of the sleeve has a lower reduced portion 280 which telescopes into the upper end of the port section 207 of the sleeve and which provides an annular downwardly facing shoulder 281 for engaging the upper end of the port section to hold the port section and the lower closure section against upward movement on the mandrel. The lower reduced portion of the top section has a reduced external annular recess in which is disposed an O-ring or other suitable sealing .means 282 for sealing between the top closure section and the port section of the sleeve.

The upper end of the top closure section is provided with an internal annular flange 284 whose upper portion is threaded to engage the external threaded portion of the mandrel 201 and whose lower portion provides the sealing surface 286 engaged by the O-ring 287 disposed in the external annular recess of the mandrel which seals therebetween.

It will be apparent that due to the provision of the nut 220 threaded on the lower portion of the mandrel and the provision of the threaded internal flange 284 of the top closure section threaded on the upper portion of the mandrel, the various sections of the sleeve are rigidly mounted on the mandrel in the relationship illustrated and described.

The top closure section is provided with a plurality of longitudinally extending elongate external recesses 290, each having an aperture 291 which is aligned with a discharge port 202 of the mandrel. A valve guide 294 is rigidly mounted in the aperture 291 and secured therein in any suitable manner, as by welding.

The stem 296 of a valve 297 extends through the aperture 298 of the valve guide and through the central apertures provided in the leaf springs 300 and 301 located in the elongate slots and whose opposite ends are rigidly secured to the top closure section by the screws 303 received in threaded bores of the top closure section. The leaf springs engage the external flange 305 on the outer end of the stem of each valve 297 and bias the valve outwardly toward the open position illustrated in FIG- URE 7 wherein the engagement of the annular shoulder 310 of the enlarge arcuate head 311 of the valve limits outward movement of the valve. The arcuate valve head when moved inwardly to the closed position, illustrated in FIGURE 6, engages the valve seat 313 about the discharge port 202 and closes the discharge port against flow of fluids therethrough. The stem of the valve has a close sliding fit with its valve guide to prevent flow of fluids therebetween. The areas of the valve 297 exposed to the tubing and annulus pressures are substantially equal so that the valve will move to open position due to the force exerted thereon by the leaf springs before the pressure within the tubing rises in value to equal the pressure in the annulus.

It will now be apparent that the gas lift valve 200 will function in the same manner as the valve 20 illustrated in FIGURES 1 through 4 to permit lifting gas to flow from the annulus through the intake ports into the passage 203 and thence through the discharge ports into the tubing only when the pressure in the annulus exceeds a predetermined value and a column of well liquids of the desired height is present in the tubing above the discharge ports.

In use, one or more of the gas lift valves 200 may be connected in longitudinally spaced locations in the tubing T. A compressible gas, such as air, is introduced into each of the chambers 255 through the filler ports 210, the ball check valves 213 opening to permit such flow of gas into the chambers. The closures 217 are then threaded into the valve seats to close their orifices. The pressure of the charges of compressible gas in the chambers 255 cause the closure members 226 to move to their closed positions in sealing engagement against the cylindrical sealing surfaces 257 of the port Sections 207 and thus close the intake ports 225. The chambers of the gas lift valves may be charged to the same pressure or to different pressures. The tubing is then lowered into position in the casing 27 of the well so that the well fluids from a producing formation flowing into the casing through the perforations 320 thereof may flow up the open lower end of the tubing string which is disposed below the usual packer P which closes the annulus between the tubing and the casing below the lowermost gas lift valve 200-.

Lifting gas is then injected into the annulus between the tubing string and the casing and the surface through a suitable regulating means. The pressure of the lifting gas in the annulus acting on the pressure differential responsive valve 297 of each gas lift valve now holds the valves 297 in engagement with their seats 313 against the force exerted by the pressure within the tubing and the force exerted by the leaf springs 300 and 301 which bias the valves toward their open positions. When the pressure of the lifting gas within the annulus exceeds the pressure of the charge of gas in chamber 255 of a gas lift valve, the closure member 226 thereof moves to open position to permit flow of lifting gas through the intake ports 225 into the cylindrical space or passage 203 between the mandrel and the sleeve 205 above the intake ports, but since the valves 297 are now in their closed positions, lifting gas may not flow into the tubing string through the discharge ports 202. When liquid rises up through the open lower end of the tubing string to a predetermined height above the discharge ports 202 of the gas lift valve whose intake ports are open, the hydrostatic pressure of the column of liquid acting on the valves 297 is effective, in conjunction with the force exerted by the leaf springs 300 and 301, to move the pressure differential valves 297 to their open positions, whereupon the lifting gas flows through the discharge ports into the tubing from the passage 202 to lift the column or slug of well liquids to the surface. The flow of lifting gas from the annulus through the gas lift valve now reduces the pressure in the annulus, since the gas flows from the annulus through the gas lift valve at a faster rate than it is being injected into the annulus at the surface. When the pressure within the annulus falls below the pressure in the chamber 255 of the open gas lift valve, the pressure of the charge of gas in the chamber 255 is effective to move the closure member 226 again towards closed position closing the intake ports 225. The further flow of lifting gas into the tubing is thus restricted although the pressure differential responsive valves are still open. As the column of liquid is expelled from the well at the surface, the pressure in the tubing decreases since lifting gas is flowing through the gas lift valve at a much reduced rate. In fact, at this time, the rate of flow, in cubic feet per minute, is theoretically identical through both the surface choke and the gas lift valve since the closure member 226 cooperates with intake ports 225 to greatly restrict or to regulate the flow through the valve. When the pressure in the tubing decreases sufficiently, the force of the pressure of the lifting gas in the annulus is effective to overcome the force of the leaf springs and the force of pressure within the tubing acting on the pressure differential responsive valves 297 to move the pressure differential valves to their closed positions. The gas lift valve is now again in its initial position wherein the intake ports 225 and the discharge ports 202 are closed. As the pressure in the annnlus again rises above the pressure in the chamber 255, the closure member again will move to its open position to permit flow through the intake ports 225 but flow of the lifting gas into the tubing through the gas lift valve will not take place again until the height of the column of well liquid in the tubing again rises to the predetermined height above the discharge ports of the gas lift valve.

The chambers 255 of the gas lift valves 200 connected in the tubing string T may be charged to the same pressure or to different pressures. For example, the chamber 255 of the uppermost valve may be charged to high pressure with each succeeding valve being charged progressively to smaller pressure so that the intake ports 225 of each valve will be opened at a lower annulus pressure than each valve thereabove. Alternatively, the chambers 255 of each of the gas lift valves 200 of the tubing string T may be charged to the same pressure and their pressure differential responsive valves 297 may be biased by the leaf springs 300 and 301 to open upon the occurrence of the same predetermined pressure differential conditions between the tubing string and the annulus. Eac'h valve will then open to permit lifting gas to flow into the tubing whenever the pressure within the annulus attains a predetermined value greater than the pressure within the chamber 255 thereof to open the closure member and the hydrostatic pressure condition within the tubing above the ports 202 of such valve reaches the desired value, i.e., the column of liquid above the discharge ports 202 of such valve attains the predetermined desired height.

It will thus be apparent that the valves 200 are provided with the closure members or valve means 226 for their gas intake ports 225 which open when the pressure Within the annulus attains a predetermined Value and with the pressure differential responsive valves 297 closing the discharge ports 202 which open when the pressure differential between the tubing and the annulus decreases to a predetermined value due to the attainment of a predetermined height by the column of liquid within the tubing string above such gas lift valve, so that lifting gas will be introduced into the tubing from the annulus only when the conditions within the tubing and the annulus provide for the most efficient utilization of the lifting gas.

It will further be seen that the annulus pressure responsive valve or closure member 226 closes whenever the pressure within the annulus decreases below the predetermined value.

In FIGURE 11 is illustrated a well in whose casing 27 are disposed two tubing strings T1 and T2, each of which is provided with a plurality of the gas lift valves 200 connected at longitudinally spaced locations therein. The open lower end of the tubing string T1 is disposed below the packer P1 which closes the annulus between the tubing string T1 and the well casing above the perforations 322 of the well casing through which well fluids from a lower producing formation flow into the well casing. The lower open end of the tubing string T2 is disposed above the packer P1 and below the packer P2 which seals the annulus between the casing and the tubing strings above the perforations 324 of the well casing through which fluids from another higher producing formation flow into the well casing, it being apparent that the well fluids from the lower formation flow to the surface through the tubing string T1 and that the well fluids from the upper formation flow to the surface through the tubing string T2.

The chambers 255 of each of the valves of the two tubing strings may be charged with a gas to the same pressure so that the intake ports of each valve will be opened when the pressure of the lifting gas injected into the annulus at the surface of the well attains the predetermined value. The pressure differential responsive valves of each valve will, however, open only when a column of liquid of a predetermined height is present in the tubing string above the discharge ports 202 thereof. No one valve will tend to remain open once it has been opened to keep the pressure within the annulus at such low value that the valves of the other string cannot open, since each valve will close once the pressure in the annulus falls below the predetermined value. Once the column of liquid above the valve which has been opened is moved toward the surface, the tubing pressure within such tubing drops to permit the pressure differential responsive valves of such gas lift valve to close and they will not again open until the predetermined hydrostatic conditions are again attained in the tubing above such valve. During the interval of time during which the column of well liquids in such tubing is again rising, the hydrostatic pressure condition within the other tubing above a particular gas lift valve thereof may reach the desired value to cause the pressure responsive valves of such gas lift valve thereof to open and permit flow of lifting gas into such other tubing. It will thus be apparent that several tubings of a single well may be provided with the gas lift valves embodying the invention and that the gas lift valves will function properly to permit lifting gas to flow into the tubing at proper locations therein to aid in moving well liquids to the surface.

If desired, of course, one or more of the tubing strings in the wall may be provided with the gas lift valves 20 or 200 and another of the other tubing strings may be provided with gas lift valves which are responsive only to the pressure within the annulus, such as the valves described in the patents to Cummings, 2,642,889, and 2,- 854,043. In this case, the tubing string equipped with the valves which are responsive only to the annulus pressure would be caused to operate by controlling the annulus pressure with an intermitter or time cycle controller mounted at the surface of the well, in the manner well known in the art, while the valves of the tubing strings provided with the valves 20 or 200 would operate in the manner described above.

The gas lift valve 20 may, of course, similarly be used with one or more strings of tubing within a well in a similar manner as the valves 200.

A modified form of the pressure differential responsive valve, which may be used in the valves 200 instead of the pressure differential responsive valves 297 illustrated in FIGURES 6 and 7, is illustrated in FIGURE 8 wherein the port section 207 of the sleeve 205 has an upper portion of enlarged internal diameter to provide an annular upwardly facing shoulder 330 which limits downward movement of a circular spider 332 within the port section and above the check valve 265. The spider is provided with an annular internal recess 333 aligned with and communicating with the discharge ports 202 of the mandrel 201. Upper and lower suitable sealing means, such as O-rings 335 and 336, respectively, are disposed in suitable external annular recesses of the mandrel 201 above and below the ports 202 thereof and above and below the internal annular flow recess 333 of the spider to seal therebetween. The spider is also provided with a plurality of longitudinal passages 338 which open downwardly of the spider into the passage 203 between the mandrel and the sleeve 205 and which open upwardly into an annular passage 341 between the upper end of the spider and the lower end of a closure ring 343 whose lower reduced end telescopes into the upper end of the port section 207 and is rigidly secured thereto by any suitable means, such as the weld 344. The closure ring is held against upward movement on the mandrel 201 by the nut 345 threaded on the upper threaded portion of the mandrel 201. A suitable O-ring or other sealing means 346 seals between the closure ring and the mandrel. The closure ring has a longitudinal bore 347 into whose upper portion pressure from the annulus may enter through the lateral port 348. The valve stem 349 of the pressure differential valve 350 extends slidably through the reduced diameter lower portion 351 of the longitudinal bore into the annular passage 341. A ball 353 is rigidly secured, as by silver solder, to the collar 356, threaded on the lower end of the valve stem 349. The ball 353 is adapted to engage the seat 358 to close the longitudinal passage 359 of the spider which communicates with the internal flow recess 333 thereof. The stem 349 is biased upwardly by means of a spring 360 disposed about the stem whose upper end engages the lower surface of the external annular flange 362 on the upper end of the valve stem and whose lower end engages the upwardly facing annular shoulder 363 of the closure ring.

It will be apparent that the valve 350 is responsive to the pressure differential between the tubing and the annulus since, when the valve is in its lower position, the pressure within the tubing acts on the circular area of the ball defined by its line of contact with the seat 358 to tend to move it upwardly to its open position while the pressure from the annulus which enters into the upper end of the bore 347 through the lateral port 348 of the closure ring acts on an area of the piston defined by the reduced diameter portion 351 of the longitudinal bore to tend to move the Valve to its lower closed position. Since these two areas are substantially equal and since the spring 360 tends to move the valve upwardly, the valve will move to its open position against the force exerted by the fluid pressure within the annulus whenever the hydrostatic pressure caused by a column of liquid within the tubing above the pressure differential responsive valve exceeds a predetermined value which is, however, smaller than the pressure within the annulus. It will therefore be apparent that the pressure differential valve illustrated in FIG- URE 8 functions in the same manner as the pressure differential responsive valve illustrated in FIGURES 2 and 6.

It will now be seen that gas lift valves of several different forms have been illustrated and described, each of which has valve means responsive to the annulus pres sure which opens when the pressure within the annulus exceeds a predetermined value and a pressure differential responsive valve means which is responsive to the pressure differential between the tubing and the annulus and which opens only when the proper pressure differential conditions exist between the tubing and the annulus so that the lifting gas from the annulus may fiow into the tubing through such gas lift valve only when the pressure within the annulus exceeds a predetermined value and the pressure differential between the interior of the tubing and the annulus decreases below a predetermined value, this occurring only when a column of liquid in the tubing attains a predetermined height in the tubing above such gas lift valve.

It will further be seen that the gas lift valves embodying the invention will close when the pressure within the annulus drops below the predetermined value regardless of the conditions within the tubing above such valves.

It will further be seen that each of the gas lift valves illustrated and described has means providing a passage, an intake port means which permits flow of lifting gas from the exterior of the valve into the passage, and a discharge port means communicating the passage with the interior of the tubing to permit flow of gas into the tubing when the valve is mounted in such tubing either in an oifset pocket, as shown in FIGURE 1, on the exterior of the tubing as shown in FIGURE 5, or connected in the tubing to form a section thereof as shown in FIG- URES 6 through 11.

It will further be seen that the gas lift valve has an annulus pressure responsive valve means for closing the intake port means which opens only when the pressure in the annulus exceeds a predetermined value and which closes when the pressure in the annulus drops below the predetermined value, and also has a pressure differential responsive valve means closing the discharge port means which opens only when the pressure differential between the tubing and the annulus decreases to a predetermined value whereby the lifting gas will be admitted by the gas lift valve into the tubing from the annulus only when the pressure within the annulus exceeds a predetermined value and a column of liquid of predetermined height is present in the tubing above the discharge port of the gas lift valve.

It will also be seen that the intake port means of each of the gas lift valves, such as the intake ports 49, the valves and the intake ports 225 of the valve 290, permit flow of fluid from a first region exterior of each valve into the passage *119 of the valve 20 and the passage 293 of the valve 260 and that the discharge port means, such as the passages 112 of the valve seat 111 and the ports 54 of the cap 53 of the valve 20 and the ports 202 of the valve 200, permit flow of fluid from such passage to a second region spaced from the first region, it being apparent that in each case the second region communicates with or is within the tubing string.

It will further be seen that while specific valve means for the intake ports employing resilient closure members have been illustrated and described for controlling fluid flow through the intake ports, other types of valve means may be employed for this purpose; for example, the bellows type valve means illustrated and described 1n the patent to King 2,339,487.

The foregoing description of the invention is explanatory only, and changes in the details of the constructlon illustrated may be made by those skilled in the art, within the scope of the appended claims without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. A valve including: means providing an internal flow passage and having an intake port means for permitting flow of fluid into said passage from a first region exteriorly of said valve and a discharge port means spaced from said intake port means for permitting flow of fluid from said passage to a second region spaced from said first region; means for preventing flow of fluid from said passage to said first region through said intake port means; first valve means in said passage and biased toward closed position preventing flow of fluids through said passage, said first valve means being responsive to the pressure at said first region for opening and closing said intake port means; second valve means in said passage downstream of said first valve means and said flow preventing means and biased toward open position; said second valve means including fluid pressure responsive means comprising a closed chamber operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; and conduit means through said means providing said flow passage directly connecting said first region with said chamber of said fluid pressure responsive means for urging said second valve means toward closing position in response to the pressure differential between the pressures of said first and second regions for opening and closing said discharge port means, said second valve means being urged toward open position by fluid pressure from said second region.

2. A valve including: means providing an internal flow passage and having an intake port means for permitting flow of fluid into said passage from a first region exteriorly of said valve and a discharge port means spaced from said intake port means for permitting flow of fluid from said passage to a second region spaced from said first region; check valve means in said passage for preventing flow of fluid through said passage from said discharge port means to said intake port means; first valve means in said passage upstream of said check valve means and biased toward position closing said intake port means and responsive to the pressure at said first region in excess of said biasing force acting on said valve means for opening said first valve means, said first valve means being biased to a position closing said intake port means when said pressure at first said region is of a value less than the biasing force acting on said first valve means; and second valve means responsive to pressure diflerential between said first and said second regions for opening and closing said discharge port means; said second valve means including fluid pressure responsive means comprising a closed chamber operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; and conduit means through said valve directly connecting said first region with said chamber of said fluid pressure responsive means whereby said second valve means is urged to port closing position by fluid pressure from said first region and is urged to open position by fluid pressure from said second region and said biasing force.

3. A valve connectable to a tubing of a well for controlling flow of fluid from the annulus of the well into the tubing, said valve including: a valve body having means providing an internal flow passage and having an intake port means for permitting flow of fluid from the annulus of a well into said passage and a discharge said annulus for closing said intake port means when the pressure within the annulus drops below a predetermined value and for opening said intake port means when the pressure within the annulus rises above said predetermined value; and second valve means in said passage downstream of said first valve means for opening and closing said discharge port means; said second valve means including fluid pressure responsive means comprising a closed chamber operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; and conduit means through said valve body directly connecting annulus pressure with said chamber of said fluid pressure responsive means, whereby said second valve means is urged to port closing position by fluid pressure from the annulus in said chamber and is urged to open position by fluid pressure from the tubing.

4. A valve connectable to a tubing of a well for controlling flow of fluid from the annulus of the well into the tubing, said valve including: a body having means providing an internal flow passage and having an intake port means for permitting flow of fluid from the annulus of a well into said passage and a discharge port means for permitting flow of fluid from said passage into said tubing; first valve means in said passage biased toward closed position and responsive to the pressure in said annulus for closing said intake port means when the pressure within the annulus drops below a predetermined value and for opening said intake port means when the pressure within the annulus rises above said predetermined value; and second valve means in said passage downstream of said first valve means and having areas exposed to fluid pressures in said annulus and within said tubing, said second valve means being responsive to a predetermined pressure differential condition between the tubing and the annulus for opening and closing said discharge port means; means biasing said second valve means toward an open position; said second valve means including fluid pressure responsive means comprising a closed chamber in said body arranged to receive fluid pressure to urge said second valve means toward closing position; and conduit means through said body directly connecting said annulus pressure with said chamber for urging said second valve means toward closing position, said second valve means being urged toward open position by the fluid pressure within the tubing and said biasing means; said pressure differential responsive second valve means moving to open position to permit flow of fluid from said passage into said tubing when the pressure within the tubing at said discharge port means rises to a predetermined value which with the biasing means acting on said second valve means is greater than the valve of the pressure in said chamber from 'within said annulus acting on said second valve means urging the same toward closed position.

5. A valve connectable to a tubing of a well for controlling flow of fluid from the annulus of the well into the tubing, said valve including: a body having means providing an internal flow passage and having an intake .port means for permitting flow of fluid from the annulus of a well into said passage and a discharge port means for permitting flow of fluid from said passage into said tubing, said valve having check valve means for preventing flow of fluid from said tubing through said port means to the annulus; first control valve means in said passage adjacent said intake port means; means biasing said first valve means toward closed position, said first valve means being responsive to the pressure in said annulus for closing said intake port means when the pressure within the annulus drops below a predetermined value determined by said biasing means acting on said first valve means and for opening said intake port means when the pressure within the annulus rises above said predetermined value; and second valve means in said passage downstream of said first valve means coacting with said discharge port means for opening and closing said discharge port means; said second valve means being biased toward open position and including fluid pressure responsive means comprising a closed chamber in said body arranged to receive fluid pressure from said annulus to urge said second valve means toward closing position; and conduit means through said body directly connecting said annulus with said chamber whereby said second valve means is urged to closed position by the annulus fluid pressure present in said chamber and is urged toward open position by the tubing fluid pressure acting with said means biasing said second valve means toward open position.

6. A valve connectable to a tubing of a well for controlling flow of fluid from the annulus of the well into the tubing, said valve including: a body adapted to be mounted in flow communication with said well tubing and having means providing an internal flow passage and having an intake port means for permitting flow of fluid from the annulus of a well exteriorly of said body into said passage and a discharge port means for permitting flow of fluid from said passage into said tubing, said body having check valve means for preventing flow of fluid from said tubing through said port means to'the annulus; first valve means in said pass-age of said valve; means biasing said first valve means toward closed position and said firstvalve means being responsive to the pressure in said annulus for movement to a position closing said intake port means when the pressure within the annulus drops below a predetermined value and for movement to a position opening said intake port means when the pressure within the annulus rises above said predetermined value; and second valve means in said flow passage coacting with said discharge port means for opening and closing saiddischarge means; means biasing said second valve means toward open position; said second valve means including fluid pressureoperated means comprising a closed chamber in said body operatively associated with said second valve means arranged to receive fluid pressure from said annulus to urge said second valve means toward closing position, and conduit means through said body wall directly connecting said annulus fluid pressure with said chamber of said fluid pressure responsive means for urging said second valve means toward closed position; said second valve means moving to open position to permit flow of fluid from said passage into said tubing when the pressure within the tubing at said discharge port means rises to a predetermined value which with the biasing means acting on said second valve means is greater than the value of the pressure within said annulus acting on said second valve means urging the same toward closed position.

7. A gas lift valve including: a body having a passage, said body having intake port means providing communication between said passage and a first region exterior of said body; said body having discharge port means spaced from said intake port means and providing communication between said passage and a second region exterior of said body; first valve means in said passage of said valve body biased toward a position for closing said intake port means and movable to open said intake port means when the pressure at said first region exterior of said body exceeds a predetermined value;

pressure differential responsive second valve means in said passage of said body downstream of said intake port valve means for closing said discharge port means and biased toward open position and having surfaces exposed to the pressure of fluid present in said first region and the pressure of fluids in said second region, said pressure differential valve means being responsive to pressures of said first and second regions; said second valve means including fluid pressure responsive means comprising a closed chamber in said body arranged to receive fluid pressure from said first region to urge said second valve means toward closing position; and conduit means through said body wall directly connecting said first region with said chamber whereby said second valve means is biased toward closing position by said pressure from said first region; the pressure of said second region tending to move said pressure differential responsive second valve means to open position and the pressure from said first region tending to move said pressure differential responsive second valve means toward closed position; and biasing means carried by said body and coacting with said fluid pressure from said second region for biasing said pressure differential responsive second valve means toward open position when the force of the fluid pressure from said second region and the force of said biasing means exceed the force of the fluid pressure from the first region acting on said second valve means urging the same toward closed position.

8. A gas lift valve for use in a landing nipple having aperture means communicating the exterior thereof with the interior thereof, said valve including: a tubular body having intake port means providing communication between the exterior and the interior of said body; closure means mounted in said body adjacent said intake port means yieldably biased toward a position closing said intake port means for controlling the flow of fluid through said intake port means into said body, said closure means being responsive to a predetermined fluid pressure acting thereon through said intake port means to be moved to an open position permitting flow of fluids inwardly through said intake port means into said body; said body having sealing means on the exterior thereof spaced above and below said intake port means, said sealing means being sealingly engageable with the walls of a landing nipple above and below the aperture means of the landing nipple when said body is disposed in the landing nipple whereby the flow of fluids through the aperture means is directed into the interior of said body through said intake port means; said body having discharge port means communicating the exterior of said body with the interior thereof at a position spaced longitudinally from said intake port means, said intake port means and said discharge port means being disposed on opposite sides of one of said sealing means whereby fluids entering through said intake port means into said body may flow through said body and outwardly through said discharge port means into the interior of the landing nipple; and pressure differential valve means mounted in said body passage downstream of said closure means and coacting with said passage and the discharge port means thereof for controlling flow of fluids from said body through said discharge port means; fluid pressure responsive means including a closed chamber in said body operatively associated with said pressure differential valve means arranged to receive fluid pressure to urge said pressure differential valve means to closing position; said body having third port means communicating said chamber of said pressure fluid responsive means directly with the exterior of said body between said sealing means for exposing said fluid pressure responsive means to said pressure from exterior of said body and between said sealing means, said pressure from exterior of said body between said sealing means tending to move said pressure differential responsive valve means toward closed position closing said discharge port means, said pressure from the exterior of said body at said discharge port means tending to move said pressure differential responsive valve means to open position, said pressure differential valve means moving to open position when the pressure at said discharge port means increases to a predetermined value which with the biasing means acting on said valve means is greater than the pressure exteriorly of said body between said sealing means acting through said third conduit on saidrvalve 20 means urging said valve means toward closed position.

9. A gas lift valve for use in a landing nipple having aperture means communicating the exterior thereof with the interior thereof, said valve including: a tubular body having intake port means providing communication between the exterior and the interior of said body; closure means mounted in said body adjacent said intake port means yieldably biased toward a position closing said intake port means for controlling the flow of fluid through said intake port means into said body, said closure means being responsive to a predetermined fluid pressure acting thereon through said intake port means to be moved to an open position permitting flow of fluids inwardly through said intake port means into said body; said body having sealing means on the exterior thereof spaced above and below said intake port means, said sealing means being sealingly engageable with the walls of a landing nipple above and below the aperture means of the landing nipple when said body is disposed in the landing nipple whereby the flow of fluids through the aperture means is directed into the interior of said body through said intake port means; said body having discharge port means communicating the exterior of said body with the interior thereof at a position spaced longitudinally from said intake port means, said intake port means and said discharge port means being disposed on opposite sides of one of said sealing means whereby fluids entering through said intake port means into said body may flow through said body into the interior of the landing nipple; and pressure differential valve means mounted in said body downstream of said closure means for controlling flow of fluids from said body through said discharge port means; fluid pressure responsive means including a closed chamber in said body operatively associated with said pressure differential valve means arranged to receive fluid pressure to urge said pressure differential valve means toward closing position; said body having third port means communicating said chamber of said fluid pressure responsive means directly with the exterior of said body between said sealing means for exposing said fluid pressure responsive means to said pressure from exterior of said body and between said sealing means, said pressure from exterior of said body between said sealing means conducted to said chamber of said fluid pressure responsive means tending to move said pressure differential responsive valve means toward closed position closing said discharge port means, said pressure from the exterior of said body at said discharge port means tending to move said pressure differential responsive valve means to open position; and, biasing means carried by said body biasing said pressure differential responsive valve means toward open position, said pressure differential valve means moving to open position when the pressure at said discharge port means increases to a predetermined value which with the biasing means acting on said valve means is greater than the pressure exterior of said valve body between said sealing means acting through said third port means on said valve means urging the same toward closed position.

10. A gas lift valve comprising: a tubular body adapted for connection in a tubing; a sleeve disposed about said body to provide a passageway between said body and said sleeve, said sleeve having an intake port, said body having a discharge port, said ports being spaced from one another; a closure member in said passage for closing said intake port to control the passage of fluid through said intake port into said passage; means for biasing said closure member toward closed position closing said intake port, said closure member moving to open position when the pressure exteriorly of said sleeve rises above a predetermined value to permit flow of fluid from exterior of said sleeve into said passage; and valve means carried by said sleeve in said passage downstream of said closure member and movable with resp ct to Said discharge port to control flow of fluid from said passage to the interior of said body through said discharge port; fluid pressure responsive means including a closed chamber in said body operatively associated with said valve means and arranged to receive fluid pressure from exteriorly of said sleeve to urge said valve means toward closing position; conduit means through the wall of said body directly connecting said fluid pressure exteriorly of said sleeve with said chamber of said fluid pressure responsive means; the pressure from exteriorly of said sleeve in said chamber of said fluid pressure responsive means tending to move said valve means to position closing said discharge port, the pressure within said body tending to move said valve means to open position permitting flow of fluids from said passage into said body, said valve means being operated by the diflerential in pressures interiorly of the body and exteriorly of the sleeve, and the closure member being operated by the pressure exteriorly of the sleeve acting in opposition to the means biasing the closure member to closed position, whereby each of said closure member and said valve means is operated independently of the other.

11. A gas lift valve comprising: a tubular body adapted for connection in a tubing; a sleeve disposed about said body to provide a passageway between said body and said sleeve, said sleeve having an intake port, said body having a discharge port, said ports being spaced from one another; a closure member in said passage for closing said intake port to control the passage of fluid through said intake port into said passage; means for biasing said closure member toward closed position closing said intake port, said closure member moving to open position when the pressure exteriorly of said sleeve rises above a predetermined value determined by said biasing means to permit flow of fluid from exterior of said sleeve into said passage; and valve means carried by said sleeve in said passage and having means exposed to the pressure of fluid exteriorly of said sleeve and to the pressure of fluid in said discharge port, said valve means being movable to control flow of fluid from said passage to the interior of said body through said discharge port; said means exposed to pressure of fluid exteriorly of said sleeve comprising fluid pressure responsive means including a closed chamber in said body operatively associated with said valve means and arranged to receive fluid pressure from exteriorly of said sleeve to urge said valve means toward closing position; conduit means through said sleeve directly connecting said fluid pressure exteriorly of said sleeve with said chamber of said fluid pressure responsive means; the pressure from the exterior of said sleeve in said chamber of said fluid pressure responsive means tending to move said valve means to position closing said discharge port, the pressure within said body tending to move said valve means to open position permitting flow of fluid from said passage into said body; and means for biasing said valve means toward open position, said valve means being movable in response to the pressure differentials acting on the means thereon exposed to the pressures from exteriorly of said sleeve and from within the body, and said closure member being operated by said pressure exteriorly of said body in excess of said predetermined value predetermined by said biasing means, whereby each of said closure member and valve means are independently operable.

12. A flow control device for controlling the flow of fluid from the annulus between two telescoped spaced flow conductors into the inner flow conductor and including: a body having means providing a passage communicating between the interior of the inner flow conductor and the annulus between the conductors; first valve means biased with a predetermined force toward a position closing off flow from the exterior of the body through the passage therein and responsive to a first predetermined fluid pressure valve within said annulus in excess of such predetermined force for permitting flow of fluids from the annulus into said passage when the pressure within the annulus exceeds said first predetermined value and for preventing flow of fluids from the annulus into said passage when the pressure within the annulus drops below said first predetermined value; second valve means within the body operable for closing off flow outwardly from said passage of said body to the inner flow conductor; fluid pressure responsive means including a closed chamber operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means conducting fluid pressure directly from the annulus to said chamber of said fluid pressure responsive means to act on said second valve means to urge the same toward closed position; and biasing means biasing said second valve means toward open position, said second valve means being responsive to the pressure within the inner flow conductor and to the pressure within the chamber of said fluid pressure responsive means conducted directly to said chamber from within the annulus for permitting flow of fluids from said passage into the inner flow conductor when the pressure within the inner flow conductor adjacent said passage increases to a second predetermined value which with the biasing means acting on said second valve means is greater than said first predetermined value whereby fluid will flow from the annulus into the inner flow conductor when the pressure within the annulus exceeds said first predetermined value and the pressure within the inner flow conductor adjacent said passage exceeds said second predetermined value, and whereby the flow of fluid from the annulus into the inner tubing will be arrested when the pressure within the annulus drops below said first predetermined value or when the pressure within the inner flow conductor drops below said second predetermined value.

13. A gas lift valve including: a body having means providing a passage and having intake port means providing communication between said passage and a first region exterior of said body and a discharge port means spaced from said intake port means providing communication between said passage and a second region exterior of said body; first valve means in said body biased with a predetermined force to a position closing said intake port means, said first valve means being movable to open said intake port means when the pressure at said first region exterior of said body exceeds a first predetermined value sufiicient to overcome said biasing force; pressure differential responsive second valve means in said body operable for closing said discharge port means and having fluid pressure responsive means including a closed chamber in said body arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means in said body connecting said first region directly with said chamber of said fluid pressure responsive means for conducting fluid pressure from said first region to said chamber to act on said second valve means for urging said second valve means toward closing position; said pressure differential second valve means having substantially equal areas exposed to the pressures of said first and second regions, the pressure from said second region acting on one of said areas tending to move said pressure differential responsive second valve means to open position and the pressure from said first region acting on the other of said areas within said chamber of said fluid pressure responsive means tending to move said pressure differential responsive second valve means toward closed position; and biasing means for biasing said pressure differential second valve means toward open position, whereby said pressure differential second valve means moves to open position when the pressure at said second region acting on said second valve means increases to a second predetermined value which with said biasing means is greater than said first predetermined fluid pressure value acting on said second valve means.

14. A gas lift valve of the character set forth in claim 13 wherein: said first valve means is movable to open position only when said pressure at said first region exceeds said first predetermined value, and said pressure responsive second valve means is movable to open position only when said fluid pressure at said second region exceeds said second predetermined value, both said first valve means and said pressure differential responsive second valve means being operable independently of each other whereby flow from said first region to said second region may take place only upon the occurrence of the predetermined pressure conditions causing movement of both said members to open position.

15. In a gas lift valve having a passage therethrough and control valve means therein biased toward closed position with a predetermined force and operable by fluid pressure of a predetermined value suflicient to overcome said predetermined biasing force to move said control valve means to open position to permit flow through the passage, whereby said control valve is responsive to said predetermined fluid pressure for controlling flow from the inlet of said passage to the outlet thereof, the improvement which includes in combination with said valve: a second valve mounted in the passage of the gas lift valve downstream of the control valve means; fluid pressure responsive means including a closed chamber in said valve operatively associated with said second valve arranged to receive fluid pressure to urge said second valve toward closing position; fluid conduit means connecting the chamber of fluid pressure responsive means directly with the exterior of the gas lift valve for conducting fluid pressure from upstream of said control valve exteriorly of said gas lift valve to said second valve; said second valve having an area thereon exposed to fluid pressure from the outlet of said passage of said gas lift valve; and means biasing said second valve toward open position; said second valve being movable to closed position when the pressure from upstream of the control valve acting through said conduit on said second valve exceeds the pressure from the outlet of the gas lift v-alve acting on said second valve plus the force of the biasing means biasing said second valve toward open position, and being movable to open position when the pressure of the fluid from the outlet of the passage plus the force of the biasing means acting on said second valve exceeds the fluid pressure from upstream of said control valve acting through said conduit on said valve means, whereby said second valve is operable by the differential in the fluid pressures acting on the pressure responsive means and the fluid pressure from the outlet of the passage to open and close the outlet of said gas lift valve in response to such pressure differential independently of the operation of the control valve.

16. A gas lift valve adapted for use in controlling flow of lifting fluid into a well flow conductor and including: a valve body having a passage therethrough communicating with the flow passage of the tubing; an inlet port in said body communicating the exterior thereof with the passage ther'ethrough; first valve means on said body controlling admission of lifting fluid from exteriorly of said valve body through said inlet port to said passage and normally biased toward closed position and openable in response to a predetermined pressure from upstream of said inlet port acting thereon in excess of said biasing force; an outlet port from said passage of said body to the flow passage of the well flow conductor; second valve means on said valve body downstream of said first valve means for controlling flow from the passage of the valve body through said outlet port to the flow passage of the conductor; means biasing said second valve means toward open position; fluid pressure responsive means including a closed chamber in said valve body operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means through the wall of the body directly connecting said chamber of said fluid pressure re sponsive means with fluid pressure exteriorly of said valve body upstream of said inlet port for conducting such fluid pressure from exteriorly of the body to said cham her; said pressure responsive means; said chamber and said conduit providing means subjecting said second valve means to pressure conducted into said chamber of said fluid pressure responsive means by said conduit means from upstream of the inlet port of said valve body; and means subjecting the opposite area of said second valve means to pressure of fluids within the passage of the flow conductor downstream of said second valve means whereby said second valve means is moved between open and closed positions in response to the differential in such pressures acting thereon; said second valve means closing off flow from said body passage through said outlet port to said conductor when the pressure from upstream of said inlet port of said valve body exceeds the biasing force acting on said second valve means plus the fluid pressure from downstream of said second valve means acting on said second valve means, the fluid pressures acting on said second valve means being operable to open and close said outlet port independently of the opening and closing of the first valve means.

17. In a gas lift valve of the character set forth in claim 16: a check valve in the passage of the body between said first valve means and said second valve means preventing back flow of fluid from said outlet port through said passage of said body to said first valve means.

18. A gas lift valve including: a body having a flow passage therein with an inlet opening and an outlet opening spaced from each other; first valve means at said inlet opening biased to closed position closing said inlet opening and responsive to the pressure of fluids from a first region upstream of said inlet opening in excess of said biasing means to open said inlet opening, said first valve means closing said inlet opening when said pressure at said first region upstream of said opening is of a value less than the biasing force acting on said first valve means; second valve means in said passage for controlling flow from said passage outwardly through the outlet opening of said body and normally biased to an open position; fluid pressure responsive means including a closed chamber in said body operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means through the wall of said body directly connecting said chamber of said fluid pressure responsive means with said first region for conducting fluid pressure from said first region to said chamber; said second valve means being exposed on one side to the pressure of fluids from a second region downstream of said outlet opening and on its opposite side to the pressure of fluids conducted into said chamber of said fluid pressure responsive means from said first region upstream of said inlet opening of said body through said conduit passage, said second valve means being moved to open position when the pressure downstream of said outlet opening plus the biasing force acting on said second valve member to move the same to open position exceeds the pressure from said first region upstream of said inlet opening within the chamber of said fluid pressure responsive means acting on the opposite side of said second valve member through said conduit passage, and closing when said pressure downstream of said outlet opening decreases below a value at which said second valve means is moved to open position, whereby the valves are operated independently of each other and said second valve will not open until the pressure downstream of the outlet opening exceeds a predetermined value with respect to the pressure upstream of the inlet opening.

19. A gas lift valve of the character set forth in claim 18 and including: check means in the passage of the body downstream of said first valve means and upstream of said second valve means preventing back flow of fluids through the passage of said body to said valve means.

20. A valve including: a body having means providing an internal flow passage having an intake port means for permitting flow of fluid into said passage from a first region exteriorly of said valve body and a discharge port means spaced from said intake port means for permitting flow of fluids from said passage to a second region spaced from said first region; first valve means in said flow passage coacting with said intake port means to close said intake port means; means biasing said first valve means to said port closing position, said first valve means being responsive to a predetermined pressure at said first region for opening and closing said intake port means; second valve means in said flow passage downstream of said first valve means and coacting with said discharge port means for closing off flow from said passage through said discharge port means; second biasing means biasing said second valve means toward open position; fluid pressure responsive means including a closed chamber in said body operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; and conduit means through the wall of said body directly communicating said first region with said chamber of said fluid pressure responsive means for applying fluid pressure from said first region to act on said second valve means for urging said second valve means to closed position by such fluid pressure from said first region; said second valve means being exposed to fluid pressure from said second region through said discharge port means for urging said second valve means to open position in coaction with said means biasing said second valve toward open position, to open said second valve means when the forces of said fluid pressure from said second region and the force of said second biasing means exceed the force of the pressure from said first region acting on said second valve means.

21. A gas lift valve including: a body having means providing a passageway therein having inlet port means providing communication between the exterior of said body and said passageway and having outlet port means spaced from said inlet port means and providing communication between said passageway and a second region spaced from said first region; a flexible resilient closure member engaging said body across said inlet port means and deformable away from said inlet port means to permit and control flow of fluids inwardly through said inlet port means into said passageway in said body; pneumatic pressure means in said body acting on said flexible closure member with a predetermined pressure to yieldably maintain said member in port closing position, whereby fluid pressure from the first region exterior of the body acting through said inlet port means on said closure member may move said closure member to an open position when said pressure exceeds the pressure of the pneumatic charge acting on said member biasing the same toward port closing position; second valve means in said flow passage of said body downstream of said first valve means and coacting with said outlet port means to control flow from said passage outwardly through said outlet port means; biasing means biasing said second valve means toward open position; fluid pressure responsive means in said body including a closed chamber operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means through the wall of said body directly connecting said chamber of said fluid pressure responsive means with said first region for conducting fluid pressure from said first region exteriorly of said body to said chamber of said fluid pressure responsive means for acting on said second valve means to move said second valve means toward port closing position; the force of said biasing means and the fluid pressure from said second region downstream of said discharge port means acting on said second valve means to move said second valve means toward open position, said second valve means being moved to open position by said biasing means and the fluid pressure downstream thereof from said second region when said downstream pressure from said second region in combination with the biasing means acting on said second valve means exceeds the closing force applied to said valve means by said fluid pressure in said chamber of said fluid pressure responsive means from said first region; and back flow check mean in said flow passage between said first valve means and said second valve means for preventing flow of fluids from said outlet port back through said passage to said first valve, whereby fluids may flow through said passageway only from said first region to said second region.

22. A gas lift valve including: a body having means providing an internal flow passage and having intake port means for permitting flow of fluids from a first region exteriorly of said body into said passage and having discharge port means spaced from said intake port means for permitting flow of fluid from said passage to a second region spaced from said first region; first valve means in said flow passage biased toward closed position for controlling flow through said intake port means and responsive to the pressure of said first region at said intake port means for opening and closing said intake port means; second valve means in said flow passage downstream of said first valve means and coacting with said discharge port means for controlling flow of fluids through said discharge port means; second biasing means biasing said second valve means toward open position; fluid pressure responsive means including a closed chamber in said body operatively associated with said second valve means arranged to receive fluid pressure to urge said second valve means toward closing position; conduit means through the wall of said body directly connecting said first region with said chamber of said fluid pressure responsive means for conducting fluid pressure from said first region to said chamber of said fluid pressure responsive means to act on said second valve means, said second valve means being exposed to such fluid pressure in said chamber from said first region exteriorly of said valve body for movement thereby to a position closing said discharge port means and being exposed to pressure from said second region through said discharge port means plus said biasing means for movement thereby toward open position, and back flow check means in said passage between said valve means and said first valve means preventing back flow of fluids from said discharge port means to said first valve means at said intake port means; said first valve means being movable to open position by predetermined fluid pressure at said first region exceeding the force biasing said first valve means toward intake port closing position, said second valve means being movable to open position by fluid pressure from said second region acting thereon with said biasing means in a value exceeding the pressure of the fluids in said chamber from said first region to open said discharge port, said second biasing means controlling the pressure differential at which said second valve means opens and closes.

References Cited by the Examiner UNITED STATES PATENTS 2,305,250 12/1942 Garrett 103-233 2,307,016 1/1943 Boynton 137155 2,588,715 3/1950 Garrett 137155 2,904,058 9/1959 Cummings 137-455 2,954,043 9/1960 Canalizo 137155 ISADOR WEIL, Primary Examiner. 

1. A VALVE INCLUDING: MEANS PROVIDING AN INTERNAL FLOW PASSAGE AND HAVING AN INTAKE PORT MEAND FOR PERMITTING FLOW OF FLUID INTO SAID PASSAGE FROM A FIRST REGION EXTERIORLY OF SAID VALVE AND A DISCHARGE PORT MEANS SPACED FROM SAID INTAKE PORT MEANS FOR PERMITTING FLOW OF FLUID FROM SAID PASSAGE TO A SECOND REGION SPACED FROM SAID FIRST REGION; MEANS FOR PREVENTING FLOW OF FLUID FROM SAID PASSAGE TO SAID FIRST REGION THROUGH SAID INTAKE PORT MEANS; FIRST VALVE MEANS IN SAID PASSAGE AND BIASED TOWARD CLOSED POSITION PREVENTING FLOW OF FLUIDS THROUGH SAID PASSAGE, SAID FIRST VALVE MEANS BEING REPONSIVE TO THE PRESSURE AT SAID FIRST REGION FOR OPENING AND CLOSING SAID INTAKE PORT MEANS; SECOND VALVE MEANS IN SAID PASSAGE DOWNSTREAM OF SAID FIRST VALVE MEANS AND SAID FLOW PREVENTING MEANS AND BIASED TOWARD OPEN POSITION; SAID SECOND VALVE MEANS IN- 